1. Field of the Invention
The present invention relates to an ultrasonic clutch, and more particularly to an ultrasonic clutch with a piezoelectric device to make a driven element move far away from a driving element when an alternating current (AC) electrical power is applied to the piezoelectric device.
2. Description of Related Art
A clutch is mounted between a driving device and a loading to make the two elements combine with each other or to separate the two elements when the clutch is actuated. A conventional clutch in accordance with the prior art substantially comprises a driving element connected to the driving device, and a driven element connected to the loading. When the driven element is attached to the driving element, the loading is connected to the driving device and actuated by the driving device.
A type of the conventional clutch comprises an engaging device arranged between the driving element and the driven element. The driving element and the driven element are connected or disconnected determined to the engagement or disengagement of the engaging device. However, the structure of the conventional clutch with an engaging device is complex, and the cost for manufacturing the conventional clutch is high. Additionally, the impact will occur when the engaging device of the conventional clutch is engaged or disengaged, whereby the structure of the conventional clutch is easily damaged and the difference of rotation speed between the driving device and the loading must be limited to a small range.
Another type of the conventional clutch comprises an engaging device with an electrical control device. The electrical control device is used to control the engagement or disengagement of the engaging device. However, the structure of the conventional clutch with the electrical control device is also complex, and the electrical control device is easily interfered with by electromagnetic waves.
To overcome the shortcomings, the present invention tends to provide an ultrasonic clutch to mitigate or obviate the aforementioned problems.